


Divergent Heart

by Redkammy (Indulgenceahoy)



Category: Undertale (Video Game)
Genre: Angst, Classic Cherry Berry, Clueless Blue, Fluff, Friends Forever, Gaster being a scientist, Gaster forgetting he is a scientist, Help the story has a mind of its own, Multi, Multirealities shenanigans, Pseudo Science, Rating may change in later chapters, Red being a general ass, Swearing
Language: English
Status: In-Progress
Published: 2020-07-13
Updated: 2020-07-13
Packaged: 2021-03-05 01:46:45
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,615
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25236391
Author URL: https://archiveofourown.org/users/Indulgenceahoy/pseuds/Redkammy
Summary: The never-ending time loops and Resets are bringing Sans to a breaking point.  Gaster wants to help his former assistant but he is stuck in the Void, so he decides to send two helpers instead.  It's the perfect solution, even if there is the chance that two other Universes will be destroyed.  Sometimes you just have to break some eggs...
Relationships: Sans/US Sans/UF Sans
Comments: 5
Kudos: 29





	Divergent Heart

**Author's Note:**

> I hope you guys like it! Many, many thanks to Lyceria for Beta reading and just putting up with me in general.

**Divergent Heart**

Chapter 1 - Possibilities

  
  


In a dimly lit room, stood a monster shaped like a man. 

He took a couple of steps forward, but it felt awkward so he took another couple of steps to his right. With a frown he considered more options. He should know where to go, but more importantly, where did he start? When did he arrive?

His mind struggled to remember those small nagging details. Perhaps they weren’t important. He was already there after all. This place was … somewhere. Something must’ve gone right … or terribly wrong. It, it was all very interesting. 

He also decided that he needed to sit down so he could consider his current situation in a more comfortable manner. 

***

The man in the shape of a monster reclined in his favorite office chair. The room was still too dark to see anything, much less read the data written on the papers on his clipboard. 

He decided he needed light to read them properly. 

***

The lamp on his desk shone upon the notes on the latest experiment run. Ah, of course, another failure. Successes were easy to acknowledge, but failures, as informative as they could be, tended to come with some degree of denial with a dash of guilt. A good scientist knew to filter those feelings out of course, but sometimes it took time. 

Sometimes it took somebody else’s help. Isn’t that - 

_ Isn’t that right -? _

***

Gaster looked upon the wall of monitors positioned over his desk. Even the scientist wasn’t sure how many of them were, as the number was soon forgotten after it was remembered. Fortunately, The only important one hung right in front of him. 

The scientist smiled upon detecting the small sleeping figure being displayed on the monitor. 

_ Isn’t that right, Sans? _

***

Gaster could not remember when he entered the Void but even if he did, he suspected that he could never go back to that point in time. 

It simply didn’t exist anymore for someone like him. 

But before that point, there was a timeline where he existed once. A scientist curious about the realm outside time and space. That timeline had continued on for the rest of them. For those Gaster could only watch through his monitors and … worry. 

At least Gaster was pretty sure he was experiencing “worry”. As close to “worry” as he could manage in his current state, anyway. It had been a while since he had a proper soul, so he was guessing what the niggling sensation in the back of his mind was. He would have given his guess a healthy 87% reliability rating if he had thought of reporting on it.

Gaster raised his eyes to look at his favorite monitor again. The Reset process was almost finished and despite its horrifying implications, it never ceased to be a fascinating event to behold. Entire towns and souls going back to points in time previously determined by the Anomaly. The most perplexing mystery out of everything Gaster had experienced. 

The Anomaly looked human, had a human soul and determination. It even didn’t look fully grown. Maybe only a couple of decades-old? Gaster had never been good about gauging human ages and failed to remember what constituted as “young” for them. There was something eerily magical about them, but not any magic the scientist was familiar with. His ongoing theory was that they had an especially powerful determination level, even for a human, but how that level had come to be able to affect the very nature of the monster world was something that still eluded him. 

He wished he could meet this human face to face, but Gaster couldn’t leave the Void and for all he knew, the Anomaly wasn’t even aware of the existence of the places in between. The only thing the scientist could do was to sit and hope that his dear assistant could figure it out on his own. 

However, after countless Resets, Gaster worried that it would never be possible for Sans to figure it out. 

Soon, his Sans would wake up with fragmented memories of his previous run. His body would ache and tire with the stress of the Reset. All monsters in the Underground could remember the Resets in a way that manifested in various ways, from feelings of Deja-vu to feelings of dread when the Anomaly showed up. Sans could remember a little more than everyone else, perhaps thanks to the experiments they carried before all of this, but even these memories were not enough. Gaster wished they’d had more time, maybe been more careful- 

If only the incident hadn’t happened. 

Gaster’s eyes wandered over the other monitors lining the wall. Each showed a different version of the world he had known. Perhaps they had been interesting at the beginning, but what the scientist knew at that moment is that he was tired of them. They were just pointless noise in a place devoid of sound. They just hung there, taunting him with all the possibilities they presented. 

Out of the corner of his left eye, Gaster saw the light from one of the monitors flicker out. This happened often enough that the scientist had grown accustomed to it. Most times, he didn’t have enough time to get to said monitor before it flickered back to life with what seemed to be a different world than the one before. This time, however, the dark monitor stayed off for an extended period of time. 

Curious despite himself, Gaster glided towards the monitor. In a very small blue font, the words “Signal Lost” flickered on the top right corner of the display. The scientist tilted his head. Well, it did make sense that there must be a signal of some kind that they were receiving. His assistant Sans had actually theorized on the existence of this very signal in the Void, which had led them to start work on a machine that might pick up on it. Of course, that had been a side project to the main Core project. 

But, this proved that there was a signal. Most likely unique to each world. Gaster couldn’t modify the monitors in any way. There were no buttons nor cables. Just floating windows. Yet, somehow, they managed to make contact with those worlds. 

Curiouser and curiouser. 

Suddenly, the monitor switched from noise to a clear signal again, which never happened without going dark before. Gaster leaned forward only to find himself taking two steps back with a gasp. The screen now showed two Sans in this world. 

How?

One of the Sanses picked the fallen one up and they seemed to have a conversation. Then the new Sans helped the other one up and they started walking together. Gaster came closer to the “screen” and looked for any signs of mixed or combined signals on the display. Nothing. This was no glitch. That new other Sans was physically there. 

Gaster had not considered the possibility of going to other timelines. Communicating with one, yeah, probably, but not physically going to one. To … actively interfere with one…

Of course!. He’d been thinking too narrow! Gaster smiled sadly. He had been by himself for far too long. The idea of help coming from outside their timeline had just been stubbornly set aside. 

He touched the screen. It felt like glass. There had to be a way he could-- it was then when he noticed the screen to the right flickering. The world that was being displayed on there didn’t look quite right. The image was distorted at the edges. Random glitches appeared at odd intervals. The monsters being shown were going about things normally but Gaster couldn’t see their Sans anywhere. If there was a constant among all these screens, it was that they seemed to faithfully follow that world’s Sans everywhere. Could it be possible that this world’s Sans was the one that came into that other screen? It looked like his absence was affecting his world of origin’s stability. 

Gaster hm’d as his mind raced. This was very exciting. 

***

Sans looked out the brightly lit windows in the Last Corridor. While he knew that the soft light imitating that of a sunset on the Surface was an illusion, he allowed himself a moment to enjoy it. He imagined that on the Surface, the version they dreamed of anyway, birds were chirping and flowers bloomed. A beautiful dream indeed. 

He hoped, for the sake of the ones that still lived by hiding in the shadows from the Anomaly, that this dream came true. His hand brushed against the tattered red scarf around his neck. His brother would never get the chance to experience the surface himself. The Anomaly had made sure of that. Sans himself had long stopped yearning for real sunlight, flowers, and chirping birds. All he really wanted was for this to just  _ stop _ . This loop. Everything. Every single time he had heard the kid walk down The Last Corridor, his entire body tensed up. This was his 34th fight inside this loop. He couldn’t remember if there had been other longer loops but it didn’t matter. 

All he knew was that he was very tired and that he missed his brother. 

It would be so easy to just let the kid walk by. 

He sighed and chuckled to himself. Never. He could never let that brother killer go. 

Papyrus deserved better. 

***

The battle between him and the Anoma-- kid had gone on for far too long. They had been better about predicting and surviving Sans’ attacks this time. The skeleton monster also noticed that while they seemed to know that they couldn’t land a hit on him due to his dodging abilities, the kid still performed wild attacks, their face alight with the sheer enjoyment of the battle.

Sans bones ached with the exertion and he could feel his power reaching its limits. He needed rest and he only had one option to achieve that. It wasn’t the smartest move but at that point, he really couldn’t think of anything else. He could hear Papyrus in the back of his mind admonishing him for being lazy, but in his soul, he was sure Papyrus was begging him to believe in that glimmer of a good person he had seen in that kid. 

Sighing, Sans performed his ultimate attack. 

“Here goes nothing!” 

****

The final blow.

Sans had wanted it to hurt but it never truly did. It was just something that  _ happened.  _ He felt his body go through the motions. Hand on his injured chest. His legs moving on their own. His mind elsewhere and everywhere. There was a better place somewhere else. He was going to Grillby’s. He was going to see his brother soon. Maybe he would like something from there. He should ask...

He would be laughing if frustrated tears weren’t choking him. 

His knees hit the floor of a dimly lit room. He knew he had been here countless times before. There were no visible walls. No door. No sound. He could feel his body being healed but his soul still felt very tired and heavy. He allowed himself a glance around the room before the rest of his body slumped towards the floor. This wasn’t death. This was so much worse. 

He closed his eyes and let his consciousness go. 

***

A kick. 

Not a hard one to hurt but strong enough to prod his mind back into consciousness. He heard a high pitched voice followed by a low growly one. Both of them sounded very familiar to him but his addled brain couldn’t quite remember the faces of the monsters they belonged to. 

Another kick. Harder this time. An exclamation of shock. 

_ ‘Papyrus?’  _ Sans thought. No, that wasn’t Papyrus’ voice. He opened one eye and spotted two short figures pushing each other around near him. “What the stars?”

The figures stopped fighting when they heard his mumble. Inexplicably self-conscious under their stares, Sans scrambled to get up. Unfortunately, the action made him dizzy and he ended up sitting back down on the hard floor. 

One of the figures rushed up to him and kneeled in front of him. “Hey, are you ok?” 

Sans blinked several times. That voice had the same inflections as his brother’s but it sounded more like … him? Not exactly, but kind of? His vision was still blurry and he wondered if he had hurt his head beyond repair this time.

“I… been better,” Sans said slowly, smiling by reflex. “Just … just give me a moment.”

“Sure why not?” Sans heard another voice say. “It’s not like we ain’t trapped in a mysterious place with cheap knockoffs of ourselves. Take all the time you want! We have nothing but _ moments _ here.”

“I absolutely refuse to believe that there is a version of myself that is so crude!” The first voice stated in exasperation. 

“Hey, looks don’t lie. Although, now that I take a better look at yah, you’re way too short to be a direct copy of me. More like a copy of a copy.” 

“COPY?!” 

Sans heard the monster that had been kneeling in front of him get up and stomp, most likely, towards the owner of the growly voice. 

“Copy of a copy,” corrected the second voice “of another copy.”

There was no excitement in this second voice. He was obviously taunting but there was a dry matter of fact tone to it. 

This voice also reminded Sans of himself. A voice he would use on his bad days, or when he was feeling especially salty. He rubbed his eye sockets some more and thankfully his vision started to clear. He looked towards the arguing pair. His eye lights grew larger then shrank when he saw them. 

_ They were him.  _

“Who -- are you?” Sans stammered. 

The other Sanses stopped in mid-argument and turned to face him. The one that sounded like his brother had bright blue eye lights and a rounder face. While the one with the growly sounding voice was taller, had red eye lights, and pointed teeth. There were more differences than that but Sans could just -feel- it in his bones. All of them were the same. 

The growly skeleton almost spat exasperated. “You know very well who we are. I can see it in your face.” He walked towards Sans until he towered over him. “We are you, but better.” 

“Rude.” Sans heard the blue-eyed skeleton say with a sigh.

“Well, -I’m- better,” continued the red-eyed skeleton with a smirk. “I don’t know about the shrimp back there.”

“HEY!”

“Great, I’m having a nervous breakdown,” said Sans. “I guess it’s about time…” 

“Nah. It’s not that simple. You know about multiple timelines and/or universes, right?” The red-eye skeleton sat down in front of him with a thud. Sans fought the urge to scoot several feet away. 

“Multiple timelines? Universes?” Sans asked. “Yeah? I guess? I remember reading about the theories. I don’t think … I know that much?” 

The red-eye skeleton leaned forward and regarded him for a minute before grinning widely. “OH, I’m SURE you know more than you think.” 

Sans felt magic sweat trickling down the back of his head. “I … do?” 

The blue-eyed skeleton walked over and sat to Sans’ right. He pushed the other skeleton back and tilted his head towards Sans. “We have reason to believe that you do.” He explained in a gentler voice. “We are here to help you so you can help us back.” He smiled warmly. 

“Help?” Sans hated sounding lost but that was what he utterly was. 

“In OTHER words,” the growly skeleton said, rolling his eyes at everyone. “We need to have a long talk.” 

***


End file.
